Casting apparatus



March 8, 1938. I E. J. LA PORTE 2,110,301

CASTING APPARATUS Filed June 6, 1936 2 Sheets-Shet 1' INVENTOR EMERYJLAPMTE.

ATTORNEY March 8, 1938. E. J. LA PORTE 2,110,301

CASTING APPARATUS- Filed June a, 1936 V 2 Sheets-Sheet 2 i N i i Z sy I INVENZFOR ATTORNEY Patented Mar. 8, 1938 STATES PATE OFFICE 2 Claims.

This invention relates generally to casting apparatus and particularly to dental casting apparatus for applying pressure to molten metal being cast to force said metal into all parts of the mold-cavity.

In the casting of delicate metal pieces such as gold dental inlays, plates and the like in a mold of refractory material the penetration of the metal into the delicately hollowed parts of the mold presents considerable dificulty on account of the physical characteristics of the gold or other molten metal. The larger the casting to be made the more difficulty is experienced.

Various means have been devised to apply pressure to the molten metal to force same into the mold-cavity but these devices have generally been imperfect and of little practical value to the profession for one reason or another or they have been too complicated and expensive and uncertain of operation for general use. For the foregoing reasons a simple, practical and efficient machine has been needed.

It is therefore the object of my invention to provide apparatus for instantly and accurately applying pressure to molten metal to force same into the mold-cavity of a mold, whether the piece to be cast be large or small.

Another important object of my invention is to provide apparatus in which such pressure may be positive and in which same may be controlled.

Another object of the invention is to provide apparatus of this character, which, because of its construction solves a very real problem, and which because of its simplicity can be produced inexpensively.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings:

Figure 1 is an elevational View of my apparatus completely assembled and ready for operation.

Figure 2 is a plan view of the same.

Figure 3 is a vertical section of the mold taken on line 33 of Figure 1.

Figure 4 is a vertical section of the base and forms for forming the plastic material of the mold cap taken on line 3- of Figure 2.

Figure 5 is a partial vertical section of the mold cap without plastic material therein.

Figure 6 is a vertical section of a mold with the mold cap thereon in position for applying pressure to the molten metal in the mold.

(C1. ZZZ-57.1)

Referring more particularlyto the drawings, which illustrate a preferred embodiment of. my invention, reference numeral Ill indicates the base of the apparatus, said base being preferably of metal and having depending legs ll for'med integrally therewith to support same. A rigid upright or post l2 extends upwardly of the base and is also formed integrally therewith, said upright having a horizontal extension l3 terminating in an enlarged vertical portion M having a vertical opening therethrough in which is slidably received a plunger l5, normally held in its upward position by a spring I3 abutting at its lower end on the top of portion #4 and at its upper end against a washer ll secured to the plunger l5 by a pin Hi. The lower end of the. plunger I5 is provided with a shoulder l9 adapted to limit the upward movement thereof.

Means for actuating the plunger l5 comprises an actuating or pressure arm 26) pivoted to the upper end of the plunger H3 at 20a intermediately of its ends. Said arm is provided with a handle 2| at its free end and is pivoted at its opposite end at 20b to the swingable end of a link 22, said link 22 being also pivoted at 23 to a pivot support 24 extending forwardly of the portion l4.

Below the plunger, in axial alignment therewith, a mold is removably mounted, said mold comprising a bottom member 25 having a depending pin 26 removably received in an opening in the base i (3 provided therefor, said bottom member 25 is also provided with an upturned flange 2'! within which is received a cylindrical casing 28 filled with a suitable investment 29 of refractory material in which is a mold-cavity of the exact size and shape of the desired metal casting, shown in the drawings as filled with metal 30. There is the customary depression 3| formed in the top of the investment and a comparatively small sprue opening, filled with metal 32, which leads down into the mold-cavity from the bottom of the depression 3!. A small amount of surplus metal 33 remains in the bottom of the depression 3|.

Above the mold, and in axial alignment therewith, is a cap 34 having an upwardly extending pin 35 fixed removably in an opening in the plunger rod l5 provided therefor, said cap 3 having a downwardly extending flange 36 within which the upper end of .the casing 28 is received.

Within the cap 34 is a plastic material 31 such as fullers earth, the inner surface 38 of which is concave and provided with an annular, marginal portion 39, the inner side of which is horizontal, said portion 39 being of the same horizontal configuration as the upper edge of the casing 28. The configuration of the plastic material facing the mold is formed by placing a quantity of said material in the cap 34 and then pressing same over a suitable form, three sizes of said form being shown on base I and numbered respectively 40, ll, and 42.

In using my apparatus the customary way of forming the mold is followed. A wax impression or pattern of the cavity. in the tooth is first made and this wax pattern is then placed upon the point of a pin by means of which same is sup- I or burn out the wax, thereby leaving the moldcavity and the comparatively small sprue open-e ing leading downwardly thereto from the de- .pression 3|;

ported in the cylindrical casing 23 while the investment material 29 is poured into positionlin" said casing. After the investment has hardened" the pin is removed and the mold is subjected to-.

a sufiicient amount ofheat to completely remove The foregoing isthe conventional way of forming a mold, althoughso far as the present, invention is concernedthemold can be formed in any desired manner.

* Informing a casting a quantity of molten gold or other metal must be placed inxthe depression 3| and some-means utilized for causing the molten plied by my apparatus to the molten metal, castings of relatively large size, such as dental plates, may be successfully made with a reduction of failures to such an extent as to almost eliminate same. No other apparatus has been placed on the market that will eflect such fine castings with such a small percentage of failures as can be secured with the present invention.

Ordinarily, with other devices, several sprue openings mustbe provided in. making large castings but with my apparatus such large castings may be successfully and satisfactorily made with jja'ri ngle sprue opening and such castings, made with my apparatus, are as fine and free from defects "as small castings.

It is thought that the invention and many of itsattendant advantages will be understood from: thefo'r'egoing. description, and it will be apmetal to 'fio-w through the sprue opening and enter the mold-cavity before the metal coolsand hardens. To facilitate this operation the mold is, of course, heated so that the molten metal will not harden when it first comes into contact therewith.

According to the instant invention pressure is applied to the moltenmetal in the mold by applying pressure-on handle 2 I which forces the plunger rod l5 and cap 34 down onto the ,mold, sufiicient pressure being available-because of the lever arrangement of the pressure applying means. The-horizontal surface of portion- 39-of'the plastic material first comes into contact with the upper edge of the casingpliland immediately and instantly causes a seal therebetwee'n. pressure on the handle compresses the air trapped in the cavity formed between the inner surface oftheplastic material 31 and the surface of the depression of. the investment material 29 and such pressure is increased by the heating and expanding of said trapped air; The pressure of the trapped air exerts pressure on the molten metal thereby forcing same downthrough the sprue opening and to all parts of the moldcavity. The space, between the flange 36 of the cap 24 and the casing 28 is small, as shown in Figures 1 and 2 and the plastic material is relatively stifi so that said material will not squeeze out of the cap 34 when pressure is applied to the molten metal in the mold.

Because of the accurate alignment and the arrangement of the various parts of the apparatus positive and instantaneous pressure maybeapplied to the molten metal in the mold and said pressure may be controlled so that any necessary and desirable pressure may be applied-by the pressure exerted on the handle.

It has been found that because of the positive, instant and controlled pressure that may be ap- Additional parentv that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit andscope of theinvention or sacrificing allof its material advantages, the form hereinbefore' described being merely a preferred: embodiment thereof.

Having thus described my invention what I claim is:

1. In apparatus of the class described, a base, a mold attached to the base, said mold having a cylindrical casing with its axis vertical, said casing having a substantially horizontal upper edge, a cylindrical cap closed at one end and: open at the other and disposed above the mold casing, the axis of the cap coincidinguwith that ofthe casing; said cap being of larger diameter than the casing and adapted to receive said casing within same, plastic material in the mold cap, the surface of said plastic material: being indented and provided with an annular horizontal portion adjacent the open rim of the cap adapt-'- ed to receive the upper rim of the-casing thereagainstto form an instant seal, and power amplifying means for applying. pressure to the cap to axially press same ontothe mold and apply pressure to the molten metal: in the mold through air, trapped in the indentation of the plastic material. I

2. In apparatus of the class described, a base, a mold attached to the base, said mold having a substantially cylindrical casing. with its axis-vertica-lly disposed, said casing having a substan- I tially horizontal upper edge; a substantially cy'- lindrical cap closed. atone end' and open at the other anddisposed above the mold casing, the

axis of the cap substantially coinciding with that of the casing, said capbeing of larger diameter thanthe casing and adapted to receive'said casing within same, plastic material inthe mold cap, the surface of saidplastic material being indented and provided with an annular horizontal portionadjacent the open rimof the cap adapted toreceive the: upper rim of the casing thereagainst to form a seal therebetween, and means for applying pressure to'the cap to axially press same ontothe mold and apply pressure to molten metal in said mold.

EMERY J. LA FORTE. 

